Repairable liquid metal/silver/hydrogel composite conductors for 3D printing

Liquid metal-based conductive materials are widely used in wearable devices, electronic skins, and flexible robots due to their excellent conductivity and stretchability. However, the inherent high surface tension of liquid metal (LM) and the limitations of its rheological properties make it difficult to continuously and stably print conductive structures. Here, a liquid metal-based conductive composite material was developed that is suitable for material extrusion 3D printing technology and possesses high conductivity, adjustable stiffness and repairable features. This was achieved by incorporating liquid metal and silver nanoparticles (AgNP) into a hydrogel cross-linked with sodium alginate (SA) and polyvinyl alcohol (PVA). The addition of these particles not only ensures conductivity but also significantly reduces the surface tension of the liquid metal. AgNP can effectively connect the LM dispersed inside the hydrogel and increase the conductive path. The conductivity of the material is as high as 19011 S cm −1 . Utilizing this conductive material, stable printing of conductors with a minimum line width of 194 μm has been achieved. Finally, the application of the proposed novel liquid metal conductor in the field of myoelectric sensors and repairable circuits fully validates the feasibility of the material.